[PATCH nf-next] netfilter: nf_defrag_ipv4: Skip defrag if NOTRACK is set

[Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>]

conntrack defrag is needed only if some module like CONNTRACK or NAT
explicitly requests it. For plain forwarding scenarios, defrag is
not needed and can be skipped if NOTRACK is set in a rule.

Since conntrack defrag is currently higher priority than raw table,
setting NOTRACK is not sufficient. We need to introduce a lower
priority rule and deprecate the existing rule.

Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
---
 include/uapi/linux/netfilter_ipv4.h | 3 ++-
 net/ipv4/netfilter/nf_defrag_ipv4.c | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/netfilter_ipv4.h b/include/uapi/linux/netfilter_ipv4.h
index e6b1a84..cedf7b4 100644
--- a/include/uapi/linux/netfilter_ipv4.h
+++ b/include/uapi/linux/netfilter_ipv4.h
@@ -57,9 +57,10 @@
 
 enum nf_ip_hook_priorities {
 	NF_IP_PRI_FIRST = INT_MIN,
-	NF_IP_PRI_CONNTRACK_DEFRAG = -400,
+	NF_IP_PRI_CONNTRACK_DEFRAG = -400, /* deprecated */
 	NF_IP_PRI_RAW = -300,
 	NF_IP_PRI_SELINUX_FIRST = -225,
+	NF_IP_PRI_CONNTRACK_DEFRAG_V1 = -210,
 	NF_IP_PRI_CONNTRACK = -200,
 	NF_IP_PRI_MANGLE = -150,
 	NF_IP_PRI_NAT_DST = -100,
diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c
index 37fe1616..6496890 100644
--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
@@ -80,7 +80,7 @@ static unsigned int ipv4_conntrack_defrag(void *priv,
 #endif
 #endif
 	/* Gather fragments. */
-	if (ip_is_fragment(ip_hdr(skb))) {
+	if (skb->_nfct != IP_CT_UNTRACKED && ip_is_fragment(ip_hdr(skb))) {
 		enum ip_defrag_users user =
 			nf_ct_defrag_user(state->hook, skb);
 
@@ -95,13 +95,13 @@ static unsigned int ipv4_conntrack_defrag(void *priv,
 		.hook		= ipv4_conntrack_defrag,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_PRE_ROUTING,
-		.priority	= NF_IP_PRI_CONNTRACK_DEFRAG,
+		.priority	= NF_IP_PRI_CONNTRACK_DEFRAG_V1,
 	},
 	{
 		.hook           = ipv4_conntrack_defrag,
 		.pf             = NFPROTO_IPV4,
 		.hooknum        = NF_INET_LOCAL_OUT,
-		.priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
+		.priority       = NF_IP_PRI_CONNTRACK_DEFRAG_V1,
 	},
 };
 
-- 
1.9.1